Rust-preventive hydrocarbon compositions



June 1, 1948. G. H. VON FUCHS EIAL 2,442,672

RUST-PREVENTIVE HYDROCARBQN COMPOSITIONS Filed Feb. 18, 1941 Ne utrolizofion Number O J J Hours Time of Exposure to Oxygen Inventors: George Hugo von Fuchs Normon B.Wi|son Patented June 1, 1948 UNITED STATES PATENT OFFICE RUST-PREVENTIVE HYDROCARBON COMPOSITIONS Delaware Application February 18, 1941, Serial No. 379,462

Claims. (C1. 252-56) This invention deals with non-gaseous petroleum hydrocarbons such as gasoline, Diesel fuel oils, lubricating oils, paraffin waxes, adhesive coatings, etc., containing small amounts of certain addition agents, which hydrocarbons possess very high anti-corrosion properties and greatly improved resistance to oxidation. The hydrocarbons of this invention are particularly well suited for use under conditions which normally result in rusting of at least part of the equipment.

It is known that the addition of relatively high molecular weight polycarboxylic acids to lubricating oils imparts to the latter anti-corrosive properties. This has been described in the Moser U. S. Patents 2,124,628 and 2,133,734, according to which polycarboxylic acids, such as polymerized oleic acid, alkylene succinic acids, etc., in lubricating oils are capable of protecting from corroding, metals which are contacted by the oil.

Now we have discovered that the addition of small amounts of anti-oxidants to non-gaseous hydrocarbons containing high molecular weight polycarboxylic acids enhances the anti-corrosive properties, provided the polycarboxylic acids are free from olefinic double bonds and are otherwise stable under the conditons to which the particular oil is exposed.

Any relatively high molecular weight saturated polycarboxylic acid, i. e., being free from olefinic double bonds. having 16 or more carbon atoms and being sufficiently stable under ordinary lubricating conditions can be used, such as polymerized and hydrogenated fatty acids, e. g., voltolized and hydrogenated lauric, palmitic, stearic acids; oleic, ricinoleic, etc., acids polymerized with a halide polymerization catalyst such as BF3 and subsequently hydrogenated, alkyl phth'alic acids, alkylated naphthalene dicarboxylic acids, such as alkyl naphthalic acid, various a1- kylated aliphatic polycarboxylic acids such as succinic, glutaric, adipic, pimelic, suberic, azelaic, tricarballylic, etc., acids. If desired, these acids may contain various substitution radicals as hydroxyl, ether, amino, nitro, hydrosulfide, sulfide, halide, etc., radicals, the most important limiting factor being the necessary stability. In general, we prefer to use a saturated aliphatic dicarboxylic acid having the carboxyl radicals as close to each other as possible and as is consistent with the requirement for stability. Malonic acid and its alkyl derivatives are known to be unstable and, therefore, cannot be used.

Substituting monocarboxylic acids, such as stearic, oleic, arachic, behemic, etc., acids, for the above polycarboxylic acids results in oils having lesser stability and poorer rust protection properties. For example, such oils allow considerable rusting of the test strip in the turbine oil rusting test described later.

The dicarboxylic acids must not contain olefinic double bonds, as it has been found that their presence renders the acids susceptible to oxidation and resultant destruction with consequent loss of corrosion protectiv properties. Under some circumstances, this loss may be very rapid, and the presence of oxidation inhibitors does not prevent or materially retard this.

The most useful dicarboxylic acids for our purpose are alkylated succinic acids having 16 or more carbon atoms and preferably those having more than 20 carbon atoms. These may be produced by reacting olefines boiling above about 300 C.such as may be obtained by cracking of paraflin wax or by dehydration of long chain fatty alcohols, etc.--with maleic acid anhydride to produce an alkylene succinic anhydride, hydrogenating to produce the alkyl succinic acid anhydried, and hydrolyzing this anhydride to produce the corresponding acid. Such acids have been described in U. S. Patent 2,133,734. As is known polycarboxylic acids of less than 16 carbon atoms have little or no corrosion inhibitor properties.

The anti-oxidants which we have found to be eii'ective in combination with the saturated dicarboxylie acids may be hydroxy or amino aromatic compounds.

Suitable oxidation inhibitors are, for example, mixed alkyl phenols, the xylenols, the 2,4,6-trimethyl phenol, the pentamethyl phenol, various methyl ethyl phenols or phenols containing isopropyl, isobutyl, isoamyl, tertiary butyl, tertiary amyl, etc., radicals; alpha naphthol, alkylated naphthols, various phenols containing amino radicals such as paramino phenol, ortho-amino phenol, parabenzyl amino phenol, alkyl amino phenols; aromatic amines, as diphenylamine, alpha or beta naphthylamine, phenyl alpha naphthylamine, alpha beta dinaphthylamine, etc. Preferred inhibitors are, on the one hand, the alkyl phenols having not less than two alkyl radicals located in the 2,4- and/or 6-positions of the phenol, at least one of the alkyl radicals being a tertiary alkyl radical and, on the other hand, the secondary amines having two aromatic nuclei attached to the nitrogen.

The amounts of both the anti-corrosive and anti-oxidant agents may vary considerably, depending upon the use to which the oil is put. Normally, the amounts are much smaller than had heretofore been considered necessary for good corrosion protective properties and good oxidation stability. This is so because the two inhibitors augment each other, both with regard to corrosion and oxidation inhibition. Thus the presence of the corrosion inhibitor which has no known anti-oxidant property results in an increased effectiveness of the anti-oxidant; and likewise, the presence of the oxidation inhibitor which has no substantial anti-corrosive properties vastly improves the corrosion protecting powers of the particular corrosion inhibitors.

Heretofore it was believed that the quantities of corrosion inhibitors required to give good corrosion protection were of the order of about .25% to 5%. While we may employ quantities of this magnitude, we have found that in combination with the anti-oxidant considerably smaller amounts of the polycarboxylic acid ranging from between .001% to .1% are usually sufflcient. The lasting effectiveness of these small amounts of polycarboxylic acids is dependent upon the presence of the anti-oxidant. The amount of the anti-oxidant, while useful up to about 5%, rarely needs to exceed 1% and effective amounts when used in combination with the corrosion inhibitor usually vary from .001% to 1%.

It is usually desirable to obtain good corrosion oxidation inhibitors have the undesirable effect tive quantities of the inhibitors. Polycarboxylic acids suitable as corrosion inhibitors as well as oxidatio ninhibltors have the undesirable effect of lowering the interfacial or surface tension of the hydrocarbon oils to result in potential emulsion difilculties when the oil comes in contact with moisture or water in crankcases. tanks, jets, etc., and it is desirable to minimize this effect as much as possible by reducing the quantities of the in-- hibitors to within the limits indicated. In this connection, it is interesting to note that the reduction of the surface tension caused by the addition of both the polycarboxylic acids and the antioxidants is considerably less than would be ex-- pected from the known eifects on interfacial tension of the individual inhibitors.

It is of advantage to have the anti-corrosion and anti-oxidant properties reside in two dif ferent types of compounds, because the antioxidant becomes oxidized in the course of its use-.

ful life. If the anti-oxidant were at the same time the anti-corrosion agent, then all protective action would be destroyed at once, since oxidation of the corrosion inhibitor renders it inefiective, as pointed out above. Moreover, since the anti-corrosion agents operate by way of coating the metal surface, the oil as a result becomes depleted of the corrosion inhibitor and also of the oxidation inhibitor if both inhibiting properties are combined in one compound. The absence of the anti-oxidant would then permit more or less rapid oxidation of the oil and formation of relatively strong acids which would have a tendency to destroy the protective coating.

Some of our inhibited lubricating oils are particularly useful, for example, as turbine oils.

In the lubricating of turbines, oil is constantly circulated from a storage system connected with the turbine to the various parts to be lubricated and back to the storage. The oil is used over a long period of time, during which time it comes in contact with the atmosphere as well as with water. This contact has a detrimental effect on the qualities of the oil in that the oil oxidizes, thereby forming acid compounds which reduce the interfacial tension between water and the oil greatly. An oil so oxidized tends to emulsify with the water. Moreover, the presence of water frequently causes rusting, particularl to portions of the governor mechanism. Metallic iron and copper, which are always used in the construction of turbine oiling systems, have a catalytic effect on oil oxidation. A good turbine oil must, therefore, be substantially rust-preventive in the presence of water, must be highly resistant to oxidation in the presence of iron and copper. and must possess a reasonably high interfacial tension against water.

Excellent turbine oils can be produced from well refined lubricating oils of the proper viscosity range, which may be about 75-750 Say. Univ. seconds at F., by adding to them about .001% to .1% of a polycarboxylicacid of the type hereinbefore described, and, in addition .001 to 1.0% of an oxidation inhibitor for hydrocarbon oils.

The combined effects on oxidation stability of small amounts of a dicarboxylic acid of the above type and a typical inhibitor is well illustrated by the curves shown in the accompanying drawing, in which neutralization number of an oil having a Say. Univ. viscosity of at 100 F. is plotted against time of exposure to oxygen under a standard set of conditions. Curve I shows the oil without addition agent. Curve 2 shows the oil containing .01% of an alkyl phenol, and curve 3 shows the same oil containing .01% of the same alkyl phenol, and, in addition, .01% of an alkyl succinic acid produced in accordance with the above description. As will be noted, the addition of the succinic acid greatly enhances the anti-oxidant efiect of the inhibitors. Further, the oil containing both the succinic acid and the inhibitor was altogether rust-preventive in a turbine oil rusting test, which is carried out as follows: a strip of clean bright steel is suspended in a sample of oil contained in a glass beaker equipped with a glass stirrer. The oil is heated to 75 C., agitated for 30 minutes, and 10% by volume of distilled water is added. The oil is stirred for 48 hours while maintaining the temperature and water concentration, and the amount of corrosion of the test strip is noted.

The oils of this invention may be further improved by incorporating therein in addition from about 1% to 10%, and preferably about 3% to 6%. of so-called blowdown oil from coke produced in the cracking of hydrocarbon oils when running to coke, as described in the co-pending von Fuchs et al. application Serial No. 314,438, filed January 18, 1940, now Patent No. 2,281,894, patented May 5, 1942.

It is understood that the compounded lubricating oils hereinbefore described can be used in the lubrication of machinery other than turbines as well. Thus they may be used in internal combustion engines or in the lubrication of a great variety of sensive equipment. The rust corrosion protective properties of the oil render it especially valuable wherever danger of corrosion or rusting exists, as in the lubrication of open bearings which may be exposed to moisture or atmospheric conditions. All that maybe necessary is to adjust the viscosity of the oil to the individual needs. The latter is well within the skill of the average lubrication engineer.

Diesel fuels such as thosehaving Say. Univ. viscosities of 32 to 350 seconds at 100 F. when inhibited with some of the compounds described above possess not only excellent non-corrosion characteristics but also a greatly reduced tendency to clog orifices of injection pumps, fuel filters, etc. This latter improvement is much greater than is due to the presence of the oxidation inhibitor and is probably due to a reduction of a metal-catalytic effect, because the polycarboxylic acids deposited on the metal surfaces of containers in which Diesel fuel is stored.

Diesel fuels, like turbine oils, must be substantially rust-preventive, because Diesel engines, especially those having unit type injectors, often encounter trouble in the fuel injectors due to corrosion of closely fitted injector parts.

The corrosion eifect of our inhibited Diesel fuels upon the metal plungers of Diesel engines was determined by immersing the clean, polished metal for 200 hours in baths maintained at 200 F. The baths contained inhibited Diesel fuel and water and were agitated by blowing air through them.

Results were as follows:

Corrosion Alkyl phenol inhibited fuel+ 1 water+air Positive Alkyl phenol inhibited fuel+1% water +alr+.001% of a C22 alkyl succinic acid Alkyl phenol inhibited fuel+1% water +air+.01% of a C22 alkyl succinic i Negative Gasolines are always subject to oxidation due to contact with air in the presence of metallic iron, copper, etc., which are oxidation catalysts, During storage in tanks, drums, etc., such fuels often come in contact with water which not only increases the rate of deterioration of the gasoline but also causes rapid rusting and decay of the storage vessels. This problem is of particular importance in the shipment and storage of aviation gasolines in drum lots in tropical countries. The presence of a trace of our polycarboxylic acids together with an oxidation inhibitor completely overcomes this difficulty. The use of the smallest eifective amounts of the polycarboxylic acids in aviation gasolines in particular is quite important in that larger quantities tend to deposit in manifolds and in valves and valve seats of gasoline engines in which the fuels are used.

Our rust-preventive combination of a saturated polycarboxylic acid and an oxidation inhibitor is also useful in protective or adhesive coatings used to protect metals during storage, shipment, etc., to stabilize the coating itself against deterioration due to oxidation and to give added protec- Slight tion to the base material against the combined eifects of air and water. The rust-preventive combination is particularly effective where the thin coating is not completely impervious to air and water.

Examples of such coatings are adhesives, such as, solutions of mixtures of polymerization products of 'butadlene or isoprene and balata or gutta. percha used for bonding rubber to metal; various resins, for example, phenol-formaldehyde resins used to varnish metal parts or to cement thin metal sheets, translucent or petroleum plastics such as petroleum resins, albino asphalts, etc., used as metal protective coatings; wax polishes containing parafiln waxes, etc.

This case is a continuation in part of our application Serial No. 341,000, filed June 17, 1940 (now abandoned).

We claim as our invention:

1. Rust-preventive lubricating oil comprising predominantly a mineral lubricating oil containing dissolved .001% to .1% of a hydrogenated and hydrolyzed product of the reaction of an olefin with maleic acid anhydride and .001% to 1% of an alkyl phenol oxidation inhibitor, said product having at least 20 carbon atoms.

2. Turbine oil comprising predominantly a refined mineral lubricating oil havin a viscosity at 100 F. of to 750 Say. Univ. seconds and containing dissolved about .001% to .1% each of a saturated alkyl succinic acid containing at least 16 carbon atoms and of an alkyl phenol oxidation inhibitor.

3. Rust-preventive, lubricating oil having improved oxidation stability comprising predominantly a refined mineral lubricating oil containing dissolved .001% to .1% of a stable saturated polycarboxylic acid having at least 16 carbon atoms and .001% to 1% of an alkyl phenol oxidation inhibitor for mineral lubricating oils having not less than two alkyl radicals, at least one of which is a tertiary alkyl radical.

4. A rust-preventive composition having improved oxidation stability comprising predominantly refined liquid hydrocarbons containing dissolved 0.001% to 0.1% of a stable saturated polycarboxylic acid having at least 16 carbon atoms and 0.001% to 1% of an alkyl phenol oxidation inhibitor for liquid hydrocarbons.

5. A rust-preventive Diesel fuel oil comprising predominantly a refined mineral oil fraction of the character of Diesel fuel oil containing dissolved 0.001% to 0.1% of a hydrogenated and hydrolyzed product of the reaction of an olefin with maleic acid anhydride, said product having at least 20 carbon atoms, and 0.001% to 1% of an alkyl phenol oxidation inhibitor for said mineral oil fraction.

GEORGE HUGO VON FUCHS. NORMAN B. WILSON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,281,676 Cook May 5, 1942 2,261,888 Rocchini Nov. 4, 1941 2,133,734 Moser Oct. 18, 1938 2,124,628 Moser July 26, 1938 2,031,930 Buc Feb. 25, 1936 2,009,480 Craig July 30, 1935 

